When a vim file is source-ed is it like including the raw text of the file into the current script is it more like executing its contents and returning to the current file?


Different languages have different semantics for this, so I won't compare, but source in Vim is not exactly like either.

For one, Vim has script-local variables, which, in practice, mean file-local.

Take these examples:

foo.vim (practically lifted as-is from :h script-variable):

let s:counter = 0
function! StartCounting(incr)
    if a:incr
        function MyCounter()
            let s:counter = s:counter + 1
        function MyCounter()
            let s:counter = s:counter - 1
let b:bar=2


let b:bar=1
source foo.vim
call StartCounting(1)
echo s:counter
echo b:bar
  • If it were simply including the raw text, I'd expect to see s:counter have a non-zero value.
  • If it were executing the contents and returning, I'd expect to see b:bar unchanged.

Instead, the output is:

Error detected while processing /tmp/bar.vim:
line    4:
E121: Undefined variable: s:counter
E15: Invalid expression: s:counter

So b:bar is changed by the sourced file, but a script-local variable defined in the sourced file is not directly accessible by the calling file.

  • Interesting. It looks like script scopes dynamically nest (like block scopes in Ruby or function scopes in ECMAScript, but dynamically, not lexically). – Jörg W Mittag Apr 10 '17 at 16:41
  • Is there a command similar to source that is equivalent to include, ie treat the file as though this text was inserted here? eg. say you had a some set commands used in some particular session, would there be a command like #insert set_commands_1 – vfclists Apr 11 '17 at 22:18
  • @vfclists source is enough for set, since set is either global (affects everything in the current Vim session) or buffer-local (affects only the current buffer if used as setlocal). It is not aware of scripts. – muru Apr 12 '17 at 0:06

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